High-temperature explosive composition containing barium perchlorate and carbazole



United States Patent 3,230,120 HIGH-TEMPERATURE EXPLOSIVE COMPOSITION CONTAINING BARIUM PERCHLORATE AND CARBAZOLE Samuel A. Pence, Jr., Houston, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex., a corporation of Texas This invention relates to a composition for use as a propellant explosive; and, more particularly, to a propellant explosive which remains stable for a substantial time while being subjected to high ambient temperatures.

In the well tool art it is customary to employ defiagrating explosives, customarily referred to as propellant explosives, for many applications not requiring the force of high explosives. These propellant explosives are generally initiated by electrical means. Typical uses of propellant explosives are found in bullet perforators, core takers, bridge-plug setting-tools, and well tool valves.

Presently available propellant explosives for the above uses usually become unreliable or unstable whenever they are subjected to ambient temperatures in excess of 300 F. for even a relatively short period of time. Thus, when such explosives are used in extremely deep well bores when often ambient tempratures substantially exceed 300 F., it is not uncommon for these explosives to fail to explode when initiated. Similarly, it is equally possible that they will explode prematurely even without electrical initiation. It will be appreciated, therefore, that when such explosives are being used in a well tool, it is imperative that every precaution be taken to avoid premature detonation and premature operation of the well.

Accordingly, should a well tool having explosive propel lants be subjected to high temperatures for a prolonged time prior to their desired time of detonation, an operator will frequently retrieve the Well tool as a matter of course and replace the explosive to avoid an accidental detonation. In addition to the obvious danger of removing explosives which can be unstable, considerable time is lost unnecessarily in retrieving a well tool as well as repositioning the tool with freshly loaded explosives.

It is therefore an object of the present invention to provide a defiagrating explosive composition suitable for service in well bores having ambient temperatures in excess of 300 F. and which will remain stable over a prolonged exposure to such extreme temperatures.

It is a further object of the present invention to provide a propellant explosive for use in explosively actuated well bore equipment, which explosive will remain stable and sensitive for substantial periods of time when subject to high temperatures.

Basically, the present invention consists of homogeneously mixing granulated carbazole and barium perchlorate particles in substantially their stoichiometric proportions to provide a deflagrating explosive that remains stable for long periods of time at ambient temperatures substantially in excess of 350 F.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments.

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The explosive composition of the present invention is prepared by homogeneously mixing particles of carbazole, C H N, in substantially stoichiometric proportions with granulated barium perchlorate, Ba(ClO for an oxidizer. The stoichiometric proportions of this explosive composition have been determined to be 8.77-parts of barium perchlorate to 1.23-parts of carbazole.

Laboratory tests were initiated to determine the effectiveness of this composition in slightly different proportions under severe ambient conditions. These tests were conducted with a test gun and target immersed in a waterfilled pressure tank maintained at an elevated pressure and temperature.

Test charges were prepared by separately encapsulating a uniform amount of each composition to be tested in a conventional case. Each charge was then tested in turn by disposing it in the test gun bore behind a conventional core sampling bullet and then detonating the charge to fire the bullet into an aluminum block or target spaced 3-inches away from the outer end of the bullet.

Each firing test was conducted by first raising the pressure in the tank to 3,000-p.s.i.g. and heating the water to R, which conditions were maintained for l5-minutes before firing. The bullets used in the tests were hollowed truncated cylinders of steel and had a diameter of 1%-in., a length of Z Az-in. and weighed 300-grams.

The tests were conducted with pharmaceutical grade (U.S.P.) compounds of great purity to eliminate the need for making corrections for trace elements. The compounds were mixed in their stoichiometric proportions and IO-grams of each test composition was tested to determine the efi'ectiveness of that composition. The results of these tests are summarized in Table 1.

TABLE 1 Percent bfy weight 0 Composition Penetration Hole Volume 7 (inches) (on. em.) B3.(C10-l) 1 CizHaN *Percentages are substantially the stoichiometric proportions in view of the great purity of the compounds used.

The stability of the explosive composition was further tested by heating sealed samples in an oven. These samples were heated at a rate of 340 F./hour to a temperature slightly over 425 F. and held at that temperature for at least two hours. After cooling, it was found that the heated compositions would still explode as readily as before and that there was no detectable differences in their burning characteristics.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall Within the true spirit and scope of this invention.

What is claimed is:

1. A defiagrating explosive for use as a propellant at high ambient temperatures consisting essentially of homogeneously mixed particles of barium perchlorate and carbazole in essentially stoichiometric proportions.

2. A defiagrating explosive for use as a propellant at high ambient temperatures consisting essentially of homogeneously mixed particles of barium perchlorate and carbazole, the barium perchlorate particles being present in an amount from about 86.0% to about 89.5% by weight.

3. A deflagrating explosive for use as a propellant at high ambient temperatures consisting essentially of homogeneously mixed particles of barium perchlorate and carbazole, the barium perchlorate particles being present in 5 an amount of 87.7% by weight.

References Cited by the Examiner Encyclopedia of Explosives and Related Items, PATR 2700, vol. 2, page C45. Picatinny Arsenal, Dover, NJ.

10 1962 (TP 270, F4 1960).

CARL D. QUARFORTH, Primary Examiner. 

1. A DEFLAGRATING EXPLOSIVE FOR USE AS A PROPELLANT AT HIGH AMBIENT TEMPERATURES CONSISTING ESSENTIALLY OF HOMOGENEOUSLY MIXED PARTICLES OF BARIUM PERCHLORATE AND CARBAZOLE IN ESSENTIALLY STOICHIOMETRIC PROPORTIONS. 